Neural Substrates of Component Lexical Semantic Processes

描述（由申请人提供）：从单词中提取含义（词汇语义）对正常的语言功能至关重要。词汇语义障碍可能由多种原因引起，包括发育异常、中风和退行性疾病，但可能反映一个或多个组成过程的损害。当前的语言模型已经确定了词汇语义系统的两个性质不同的组件：1）自动组件能够在词汇输入的几毫秒内快速访问语义; 2）受控组件进化得更慢，并指导策略检索语义信息。此外，与这些成分相关的一些过程被认为取决于传入刺激的方式。该项目的目标是确定这些行为可分离的词汇语义系统的自动和控制组件的神经相关，在视觉和听觉模态内和跨视觉和听觉模态。在一项初步研究中，我们确定了可分离的神经相关的视觉提示自动和控制词汇语义处理的健康志愿者使用事件相关的功能磁共振成像和启动词汇决策任务。一系列类似的研究，提出了更准确地描述的几个额叶和颞叶脑区的词汇语义系统的组成部分的作用。该设计是新颖的，自动和控制语义启动条件将直接比较，使用随机设计中使用的行为研究。有三个目标。第一个目标是更准确地描述视觉线索控制检索词汇语义信息的左额叶区域的作用。第二个目标是更精确地描述左颞区在视觉线索自动词汇语义处理中的作用。第三个目标是确定神经区域参与courageorily线索词汇语义重叠，并分离，参与视觉线索词汇语义。识别与从单词中提取意义的组件过程相关的神经系统对于理解词汇语义系统的结构和组织至关重要，并且应该有助于语言障碍的诊断和康复。

DESCRIPTION (provided by applicant): Extracting meaning from words (lexical semantics) is critical to normal language functioning. Lexical semantic impairment can result from a variety of causes including developmental abnormalities, stroke and degenerative diseases but may reflect damage to one or more component processes. Current language models have identified two qualitatively different components of the lexical semantic system: 1) An automatic component enables rapid access to semantics within milliseconds of lexical input; and 2) a controlled component evolves more slowly and guides strategic retrieval of semantic information not recovered automatically. In addition, some processes associated with these components are thought to depend upon the modality of incoming stimuli. The objective of the project is to identify the neural correlates of these behaviorally separable automatic and controlled components of the lexical semantic system, within and across visual and auditory modalities. In a preliminary study, we identified dissociable neural correlates of visually cued automatic and controlled lexical semantic processing in healthy volunteers using event-related fMRI and a primed lexical decision task. A series of similar studies are proposed to characterize more precisely the roles of several frontal and temporal lobe brain regions in components of the lexical semantic system. The design is novel in that automatic and controlled semantic priming conditions will be compared directly, using randomized designs identical to those used in behavioral research. There are three goals. The first goal is to characterize more precisely the role of a left frontal region in visually cued controlled retrieval of lexical semantic information. The second goal is to characterize more precisely the role of a left temporal region in visually cued automatic lexical semantic processing. The third goal is to identify neural regions involved in auditorily cued lexical semantics that overlap, and are dissociable from, those involved in visually cued lexical semantics. Identifying neural systems associated with component processes involved in extracting meaning from words is of central importance to understanding the structure and organization of the lexical semantic system and should aid diagnosis and rehabilitation of language disorders.